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Air Infiltration - The amount of air leaking in and out of a building through cracks in walls, windows and/or doors.

Argon Gas - An odourless and colourless inert gas in double and triple-pane sealed glass units (used for thermally broken window and door units) that helps to reduce heat transfer through the glass.

Astragal - The center member of a double door, which is attached to the fixed or inactive door panel.

Awning Window - An operating style of window with a sash hinged on the sides which swings open from the bottom towards the exterior.

Bay Window - A three-unit combination window consisting of a central picture or fixed window flanked by a pair of operable (opening) windows set at an angle (usually 45 degrees).

Bow Window - A type of window consisting of four or more window units attached at an angle to give the impression of a curve.


Brickmould - Decorative perimeter or border that encases the entire window and is visible from the outside of the house.

Casement Window - An operating style of window with a side-hinged sash that opens from the hinged side towards the exterior.

Casing - Molding of various widths, thicknesses and shapes applied to the framework of window and door units.

Caulking - A sealant used to seal construction joints to prevent water and air infiltration.

Cladding/Capping - A material - usually aluminum - locked to the outside faces of many products to provide a durable, low-maintenance exterior surface.

Combination Window - A combination of two or more complete window assemblies of the same or different types that are mulled together.

Condensation - Moisture formation on touchable surfaces of glass on doors or windows due to cold temperatures, high humidity levels and poor airflow.

Double-glazed - Two single pieces of glass with a spacer create a double-glazed unit. One or more glass pieces may have an LoE coating. Between the glass, the spacers keep the moisture, air and debris out of the unit while keeping the argon gas in.

Double Hung Window - An operating style of window with an upper sash that slides down and a lower sash that slides up.

Dry Glazing - A method of securing glass in a window frame with a dry, preformed, resilient gasket, without the use of a glazing component.

Egress - The space in which the operating part of the window requires clearance for fire regulations.

Energy Star - A volunteer organization in partnership with the government of Canada and windows and door industry leaders to ensure high-efficiency products. The ENERGY STAR® symbol is an internationally recognized and trusted mark of high efficiency. The symbol means that a product, home, building or industrial facility is certified as energy efficient.

GEM is the winner of the ENERGY STAR Retailer of the year award for 2018 and 2019.

Extension Jambs - Flat wood or vinyl parts that are applied to the inside of the frame to extend it in width, which allows the frame to adapt to a thicker wall.

Exterior Glazed - Glass installed from the exterior side of the window. Fixed unit – A stationary window or door unit that does not open.

Flashing - A thin strip of metal or synthetic material that diverts water away from a window or skylight.

Frame - The enclosing box of a window or door that surrounds a sash or sealed unit, consisting of a head, sill and two jambs.

French Door (aka Garden Door) - Garden doors feature two door panels with one used as an entryway and the other used for ventilation. Similar to a swinging patio door, garden doors make excellent entry points to outdoor recreation areas like backyards, gardens and patios. Garden Doors have two doors, but only one of the doors can open and close for passage. On the other hand, French Doors have two opening doors, which offer a larger opening.

Glazing Stop - Used to hold the glass into the frame.

Grille (Muntin Bar) - Dividing Bars or Muntins used either on the surface or between panes of glass for a decorative appearance.

Half-Round Window - True half-round where the arch comes right down to the sill. The height is half the width.

Head and Seat - Attached to the top and bottom of a bay or bow window as an option where the wall is not framed to follow the angle of the window.

Hopper Window - A window unit in which the top of the sash swings inward. Often used as an Egress window.

Inside Casing (Trim) - The mouldings that surround the window and cover the frame on the inside wall of the building.

Insulating Glass Unit (IG or IGU) - A combination of two or more panes of glass factory sealed using a spacer bar. Also known as a sealed unit.

Interior Glazed - Glass installed from the interior of the building.


Jamb - The side components of a window or door frame.

Krypton Gas - A rare atmospheric gas that is odourless, colourless, tasteless, nontoxic, monatomic and chemically inert. It is considered a better insulator than argon gas.

Low Emissivity Glass (LoE) - LoE is a thin metallic layer that is applied directly to a glass (glazing) surface. A basic coat is virtually invisible, as more layers are added a slight change in tint may occur.

Mullion - An extrusion that joins windows. A sealant is applied between the units to prevent air and water leakage. A bullnose or profiled moulding is used on the inside and outside to cover this joint.

Multipoint Hardware - A single deadbolt that will engage additional locks into the frame of the door for added security and a tighter seal when closed.

Multipoint Latch - Uses a single latch to engage multiple locks around the windows for stability & safety and also provides a tighter seal for improved energy efficiency.

Nailing Fin - A vinyl or metal flange attached to the perimeter of a window frame for insulation onto the rough opening header, jack studs and rough sill.

Operator - Refers to a door or a window that has an operable sash or panel that opens to allow passage or ventilation.


Patio Door - A sliding door consisting of a panel fitted with an insulated sealed unit, with one operating panel sliding horizontally to provide passage. Sometimes available in three or four-panel configurations (with some panels fixed and others operable).


Picture Window - A type of window in which a sealed unit is glazed directly into the window frame, without a sash.


Polyurethane Core - An insulating foam material, doors are foam injected for higher insulating value.


R-Value - A term used to express the insulating values of a material or unit. A higher R-value indicates better insulating properties.


Relative Humidity - Humidity expressed as a percentage of the maximum possible humidity at a given temperature.


Rough Opening - The opening built into a frame wall to receive a window or door unit. A rough opening is unfinished from both the exterior and interior.


Sash - A sub-frame component that surrounds a sealed unit. A sash can be either fixed (non-operating) or operating.


Sash Balance - A coiled spring or spiral system integrated into the jamb liners to allow double-hung or single-hung sashes to open and close.


Sealed Unit - A combination of two or more panes of glass factory sealed using a spacer bar. Also known as an insulating glass unit (IGU).


Shims - Rubber setting blocks used to position the glass into the window to ensure it is level, square and plumb.


Sidelite - A narrow fixed or operating unit joined to the side of a door frame combination.


Sill - The bottom component of a door or window frame.


Simulated Divided Lites (SDL) - A decorative exterior grill bar that is placed on a full/single glass unit. Interior guide bars may be between the glass. This creates the visual effect of dividing the glass into small units.


Single Hung Window - An operating style of window with a fixed top panel and a lower sash that slides up vertically.


Skylight - A window designed for roof installation, usually to provide natural light to interior building areas.


Slider Window - A type of window with one fixed sash and one or two units that slide sideways.


Solar Heat Gain Coefficient - A measurement of how much solar energy a glass combination will allow to pass through. A higher coefficient allows more potential solar heat gain than a lower coefficient.


Solar Transmittance - The percentage of total solar energy that glazing transmits through a window.


Sound Transmission Class - Rates the ability of glazing to block out sound from outside sources.


Spacer Bar - The strip of material that maintains uniform separation between the layers of glass in the sealed unit of the window.


Steel Insulated Door - Hot dipped galvanized steel sandwiched with polyurethane foam insulation. Pinewood framing, treated against rot, helps maintain structure and helps prevent warping. Some manufacturers use composite materials as an alternative to wood.


Stops - A window component that holds the sealed unit into a frame or sash.


Tempered Glass - A heat/chemically treated glass to withstand more force than regular glass. If broken, the tempered glass will shatter into small chunks (not large jagged or sharp pieces). Required in many Canadian and International building codes.


Thermally Broken - A space or insulating material used to create a break on conductive materials, helps reduce heat transfer.


Transom - A window unit combined with the top of a window or door frame.


Triple Glazed - Three single pieces of glass with 2 spacers create a triple-glazed unit. One or more glass pieces may have an LoE coating. Between the glass, the spacers keep the moisture, air and debris out of the unit while keeping the argon gas in.


True Divided Lites (TDL) - Individual small units of glass are installed into frames with glass stops. The frames are based on the pattern design.


U-Value - A measurement of heat transmission.


Visible Light Transmittance - The percentage of visible light that is transmitted through a glazing combination. The type of sealed unit, coatings and tints will affect the percentage of visible light transmittance.


Weather Stripping - A material used to create an air or water seal between operating components of a window or door.


Wind Load - The amount of pressure exerted by the wind on a window or door generally expressed in pounds per square foot.


Woodgrains - Textured material to emulate a real wood look.

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